The purpose of the proposed research is to develop an isolated breeding facility for marmosets with semi-outdoor conditions. Marmosets will be housed in family unit breeding modules of adjustable size with heated nesting boxes and automatic water supply. Each family unit will be visually screened from all other family units. Cage enclosure construction will permit exposure to fresh air and sunshine, and provide protection against the elements during inclement weather. The Facility will be appended to the existing Marmoset Research Center, but we will limit access to feeding, observation, and health care of the animals. Most family units will be undisturbed until the birth of the 3rd litter. We will make observations of the social and reproductive behavior under these conditions with the aid of remote closed circuit television monitoring. Breeding families will include 33 pairs of Saguinus oedipus oedipus, 18 pairs of saguinus fuscicollis illigeri and 8 pairs of Callithrix jacchus the first year. 28 additional pairs will be added the 2nd year, including 14 pairs of S.o. oedipus presently on hand. Our objectives are to propagate these species to sustain current and proposed research independent of outside supply, and to make marmosets available for use by investigators from ORAU Member Universities for projects of scientific merit that require investigation in primate species.